INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 7 ISSUE 1 – JULY 2015 - ISSN: 2349 - 9303
Novel Design of VLT CUK Converter
B.Hariprasath
R.Senthilkumar
PG Scholar
Department of Electrical and Electronics Engineering
Bannari Amman Institute of Technology, Tamilnadu, India
E-mail: haripasatheee08@gmail.com
Professor
Department of Electrical and Electronics Engineering,
Bannari Amman Institute of Technology, Tamilnadu,India
E-mail: ramsenthil02@gmail.com
ABSTRACT: The main purpose of this paper was to create a novel topology of CUK dc/dc converter. This thesis talks about the
importance of dc-dc converters and why CUK converters are used instead of all other dc-dc converters. This project also goes into
detail about analysis of CUK converter with novel voltage lift technique optimization and control. All the basic converters results are
compared with novel topology by using PROTEUS software.
Keywords: VLT (Voltage Lift Technique), CUK converter, PROTEUS .
I.
INTRODUCTION:
DC to DC converters are essential in portable electronic
gadgets such as cellphones, laptop, computers, car auxiliary power
supplies, industrial applications and medical equipment which are
supplied from batteries. Such electronic devices had several sub
circuits which require unique voltage like higher or lower than the
battery voltage, or even negative voltage.
DC to DC converters offers multiple controlled DC
output voltages from a single variable battery voltage, instead of
using multiple batteries to supply different parts of the electronic
devices.
These converters will be widely used in computer
peripheral equipment and industrial applications, especially for
high output voltage projects. In recent years, the DC-DC
conversion technique has been greatly developed. The main
objective is to reach a high efficiency, high power density and
topology in a simple structure. There are 5 main types of dc-dc
converters.
Buck converter, Boost
converter, Buck-boost
converter, CUK
converter, SEPIC
converter.
Buck converters can only reduce voltage, boost
converters can only increase voltage, and buck-boost, CÚK, and
CUK converters can increase or decrease the voltage. Another
issue that can complicate the usage of buck-boost converters is the
fact that they invert the voltage. CÚK converters solve both of
these problems by using an extra capacitor and inductor.
However, both CÚK and buck-boost converter operation
cause large amounts of electrical stress on the components,
this can result in device failure or overheating. CUK
converters solve both of these problems. The CUK converters
are good topologies which have been developed. Because of
the effect of parasitic elements, the output voltage and power
transfer efficiency of all DC-DC converters is restricted.
The voltage lift technique is a popular method
widely applied in electronic circuit design [1-9]. It can lead to
improvement of DC-DC converter characteristics. After long
term research, this technique has been successfully applied to
DC-DC converters.
(a)
(b)
Figure 1.1(a): Triple lift 1.1(b) Multiple lift
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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 7 ISSUE 1 – JULY 2015 - ISSN: 2349 - 9303
2. ANALYSIS OF DC – DC CONVERTERS
frequencies. They had a freewheeling diode to protect the
active switch from the inductors reverse currents.
There are many topologies available
i) Self-lift circuit [8][12]
ii) Re-lift circuit [11]
iii) Multiple-lift circuits[2][5][9] (e.g. triple-lift and
multiple-lift circuits) showed in Figs. 1.1(a) & (b)
respectively.
Features of a buck converter:
It requires input filter with pulsed current. It delivers
continuous output current. It leads to lower voltage ripple.
Features of a boost converter:
In boost converter no need for input filter. It
increases the voltage ripple. Load voltage is always greater
than input supply voltage.
This project introduces the skills to design new lift dc–
dc converters using voltage lift technique. Lift converters are a
group of new dc–dc step-up converters, which are developed
from the basic prototypes [1]–[7].
Features of a buck - boost converter:
Pulsed input current, requires input filter. Pulsed load
current increases voltage ripple. Load voltage can be either
greater or lesser than supply voltage.
Features of CUK converters:
Continuous input and output current. Load voltage
can be either greater or lesser than input voltage.
The conventional method which have been already
implemented are,
i)
Self-lift converter
ii)
Self-lift positive output converter.
iii)
Self-lift negative output converter.
iv)
Self-lift CUK converter.
Features of SEPIC converters:
Like buck–boost converters, SEPIC have a pulsating
output current. Since the SEPIC converter delivers all its
power via the input series capacitor. The capacitor with high
capacitance and current handling capability is required.
The above listed methods are described with
following Schematic representations.
3. VOLTAGE LIFT TECHNIQUE:
Voltage lift technique is an efficient method widely
applied in design of electronic circuits. In recent years it has
been successfully employed in DC-DC converter applications,
and builds a way to design high-voltage gain converters. VLT
converters [8-9] are different from any other DC-DC step-up
converters. It has many advantages including the high output
voltage with smooth ripples. But existing converters are not
economical, Because of the effect of parasitic elements, the
output voltage and transfer gain of converters is limited. In
order to overcome these limitations and to make efficient
converter with a simple new technique called voltage lift
technique. The performance of VLT converter is superior with
the following credits.
(I) It can perform similar to classical boost converter
with high-voltage transfer ratio.
(ii) Wide range of control with smooth ripple at the
output voltage.
(iii) High power density
(iv) Comparatively high efficiency than classical
boost converter.
In this proposed method all the components that are
ideal and the capacitors values are large enough and also
assume that the circuits operate in continuous conduction
mode. This circuit consists of passive components: one static
switch (Power MOSFET), two diodes, four inductors and two
capacitors perform the characteristics to lift the output voltage.
The basic principle of this circuit is enhance the
output voltage by charging and discharging reactive elements
into a load, and consequently controls the output voltage by
switching the source in and out of the circuit at very high
Fig 3.1 Self-lift converter.
Fig 3.2 Self-lift positive output converter.
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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 7 ISSUE 1 – JULY 2015 - ISSN: 2349 - 9303
5.
DESIGN
CONVERTER
OF
NOVEL
TOPOLOGY
CUK
Inductor Selection:
A good rule for determining the inductance is to
allow the peak-to-peak ripple current to be approximately 40%
of the maximum input current at the minimum input voltage.
Input Capacitor Selection
Fig 3.3 Self-lift negative output converter.
Similar to a boost converter, the CUK has an inductor
at the input. Hence, the input current waveform is continuous
and triangular. The inductor ensures that the input capacitor
sees fairly low ripple currents.The input capacitor should be
capable of handling the RMS current. Although the input
capacitor is not so critical in a CUK application, a 10μF or
higher value, good quality capacitor would prevent impedance
interactions with the input supply.
6. SPECIFICATIONS:
The converter should meet certain standards
Fig 3.4 Self-lift SEPIC converter.
S.no
4. PROPOSED MODEL:
The proposed methods develop a new series of DCDC step-up (boost) converters namely modified CUK
Converters which eliminates the auxiliary switch in the
original Positive Output Converters yet perform the same
functions.
Values
1
2
3
Parameters
Vin
Vout
Duty cycle
4
5
Iout
Fsw
6
7
Inductor
Input
capacitor
Output
capacitor
Load
8
9
12V
-15.2V
31% to
71%
-1.2 A
20KHZ
to
50KHZ
500uH
220uF
47uF
100R
Table 6.1 design specifications of Modified CUK converter
Fig. 4.1 Modified CUK Converters.
Thus modified CUK converters (Fig 4.1) have been
used in high voltage regulated power supply. Detailed analysis
is given in the following sections. The elementary circuit
(CUK or Zeta converter) which can perform both step-down
and step-up DC-DC conversion.
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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 7 ISSUE 1 – JULY 2015 - ISSN: 2349 - 9303
7. SIMULATION AND EXPERIMENTAL RESULTS OF
SELF-LIFT CUK CONVERTER
Modified CUK converter with Voltage Lifting technique
has been designed and compared with basic DC- DC (Buck,
boost, CUK) converters model and simulated using
PROTEUS software and the results were obtained are
discussed in this chapter.
I)
Buck converter
Figure 7.4: Waveform of Boost Converter
III)
CUK converter
L1
C3
IL1
L2
Id
Ics
220uH
12V
Q1
C2
100uF
PWM
TD=0
TR=100n
TF=100n
PW=81%
FREQ=50000
V1=0
V2=12
IRF540N
D1
6TQ045
Figure 7.1: Simulation Model of Buck Converter
Figure 7.5: Simulation Model of CUK Converter
Figure 7.2: Waveform of Buck Converter
II)
Figure 7.6: Waveform of CUK Converter (31%)
Boost converter
Figure 7.3: Simulation Model of Boost Converter
Figure 7.7: Waveform of CUK Converter (81%
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VOUT
2.2uF
IL2
VIN
IOUT
220uH
VDS
C1
RL
330uF
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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 7 ISSUE 1 – JULY 2015 - ISSN: 2349 - 9303
The modified CUK topology fig 4.1 shows that it can be
act as both buck and boost converter .whenever the duty cycle
below 50% CUK converter act as buck converter but in this
case the modified CUK converter delivers the output power
higher than the input when the duty cycle is 31%.
IV) Modified CUK converter
From that we conclude that it lifting the voltage even
below the 50% duty cycle. Lifting topology can be varied like
triple lift, multiple lift. Whenever the lifting components L-DC-D increase the switching loss can be minimized. Here the
value of lifting component L=500uH and C= 22uF connected
parallel with input inductance which stores and deliver the
power to the load. During On condition it stores the energy
and During Off condition it Lifting the energy and deliver to
the load .This topology has been simulated under the
switching frequency about 50K and duty cycle varied about
31% to 71%.
Figure 7.8: Simulation Model of Modified CUK Converter
8. CONCLUSION:
The consequences on implementation of a Modified
Converter with Voltage lifting technique and compare with
basic buck-boost converters are investigated in this thesis.
This paper introduced an implementation method of the VL
technique in the traditional CUK converter. The simulation
model is developed for Modified CUK converters with voltage
lifting component. From the analysis and simulation results, it
is seen that the proposed novel VL-type converters can greatly
increase the voltage conversion ratios without resorting to
higher values of duty ratio. The Modified CUK converter
simulation results and waveforms has been verified and
compared with buck, boost, and normal CUK converter.
Figure 7.9: Waveform of IL1 and IL2 for modified CUK
Converter (31%)
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Figure 7.10: Waveform of Vout for modified CUK
Converter (31%)
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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 7 ISSUE 1 – JULY 2015 - ISSN: 2349 - 9303
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